This PDF file contains the front matter associated with SPIE Proceedings Volume 7926, including the Title Page, Copyright information, Table of Contents, and Conference Committee listing.

We consider mid-infrared (5 - 25 μm), optically cooled detectors based on a microcantilever sensor of the radiation pressure. The significant enhancement of sensitivity is due the combination of low effective temperature (10 K), non-absorption detection and a high quality optical microcavity. Spectrometry applications are analyzed. It is shown that an optically cooled radiation pressure sensor potentially has an order of magnitude better sensitivity than the best conventional uncooled detectors.

The fabrication of optical components based on UV-replication is spreading rapidly in the field of high volume and low cost production. Hereby, a master stamp providing optical surface quality is imprinted into a liquid polymer material which can be cured under UV-exposure. Most prominent is the fabrication of miniaturized camera objectives for mobile phone applications done on wafer level. The required lens surfaces possess high sag and aspherical shape which leads to a challenging fabrication of the master stamp which consists of an array of identical convex or concave optical surfaces. We analyze the endurance of the stamp used in a step & repeat process for the fabrication of array-like structures used as master molds for UV-replication.

The temperature dependence of the refractive indices of 4H-SiC, GaN, and AlN were investigated in a wavelength range from the near band edge (392 nm for SiC, 367 nm for GaN, and 217 nm for AlN) to infrared (1700 nm) and a temperature range from room temperature to 512°C. Optical interference measurements with vertical incident configuration were employed to precisely evaluate ordinary refractive indices. In visible region, the thermo-optic coefficient of GaN has the largest value in these materials. Optical simulation of GaN-based tunable band-pass filter with AlGaN/GaN distributed Bragg reflectors (DBRs) was also carried out by using the obtained thermo-optic coefficients. It revealed that 9 nm red-shift can be obtained from room temperature to 500°C.

In this paper processing of transparent materials by laser radiation from various sources with short (nanoseconds) and ultrashort (femtoseconds) pulse lengths at different wavelengths is discussed. The investigations were carried out with a short pulse Nd:YVO₄ laser (1064 nm, 532 nm) and a high repetition rate femtosecond fiber laser (1030 nm). In our experiments the laser beam was guided across the probe either through the motion of a coordinate table or through a laser scanner with an f-theta-objective. In our study we investigated in detail the influence of important process parameters like wavelength, pulse width, and irradiation regime upon micro defect generation inside bulk glass (BK glass, fused silica) and polymers (polymethylmethacrylate, polycarbonate, cyclo-olefin-copolymers). By applying an irradiation regime with optimal process parameters these locally confined material defects can be aligned as to yield cut surfaces for the excision of 3d parts that consist of transparent material with bulk properties. Especially for the production of irregularly shaped 3d parts a CAD-CAM software tool was developed that automatically converts geometry data into a processing program.

Laser texturing is extensively investigated for modifying surface properties. A continuous wave (CW) fiber laser (λ= 1090nm) was used to pattern a silicon wafer surface in ambient and O₂ atmosphere respectively. The O₂ gas stream was delivered through a coaxial nozzle to the laser spot. Characterization of the patterned features was carried out by surface profiling, scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS or EDX), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Formation of laser-induced silicon oxide sub-micron bumps was observed, which were analyzed and shown to cause changes in surface wetability and reflectivity.

The miniaturization of actuators results in two major consequences: First, the reduction in efficiency depending on the physical principle. Second, the increasing requirements in positioning accuracy during the assembly and fabrication process in combination with low cost production. Electrostatic polymeric actuators providing out-of-plane motion which can be completely fabricated in parallel fabrication steps and hence be produced on wafer level are compliant to these tolerance and cost constraints. The electrostatic actuation principle is a surface effect and therefore independent of the volume. In addition, the efficiency of electrostatic actuation increases with a decreasing gap size between the electrodes. The simple morphology of such actuators can be easily produced by UV-replication of polymeric materials. In consequence, the electrostatic actuation principle is predestined for the combination with low cost wafer level fabrication. This paper reports on the first results of successfully fabricated electrostatic actuators produced on wafer level. Instead of using a standard silicon substrate our approach is based on the lithographic structuring of the non-conducting material ORMOCER®. In comparison ORMOCER® has a significantly lower elastic modulus (about 1 GPa). Therefore, only a fraction of actuation voltage is necessary for a similar deflection. The material is structured using photolithography and the electrodes are realized with coatings of thin metal layers. Experimental results show a deflection up to 49,1 μm at 500 V for an 75 μm thick cantilever beam fixed at both ends. Good agreement between measurements and simulations is achieved, proving the applicability of the software and the assumed material parameters.

This paper presents a new approach to fabricate low cost metallization on PMMA substrates based on commercially available Mirrored-Extruded Acrylic (mirrored Plexiglass / mirrored PMMA). The patterned metal could be subsequently employed as a mask for deep-UV PMMA micropatterning of polymer-MEMS devices. The process presented eliminates the use of sputtered metals and can be scaled up to substrates of sizes 12 inch × 24 inch or larger for batch fabrication. Mirrored Extruded Acrylic has a coating of 6 micron thick vacuum metalized aluminum or copper with an adhesive backing. We have discovered that the adhesive backing can be easily etched away by using ethanol, exposing the aluminum or copper, which can be micropatterned by standard photolithographic processes. We have fabricated various microstructures in aluminum, including microelectrodes and Van de Paw structures. Resistivity measurements show that the resistivity of the micro-machined aluminum is equal to lower than 4.8 × 10^-6 Ω-m, which is sufficient for sensor electrodes or signal routing applications for MEMS/ MST devices.

An electrostatic-actuated suspended bridge structure composed by single-crystalline silicon carbide (SiC) is fabricated. The structure is entirely made of homoepitaxially grown single-crystalline 4H-SiC. Electrical isolation between the suspended bridge and the base plate is established with a pnp junction formed by multiple ion implantation. The structure is fabricated by a combination of reactive ion etching (RIE) and doping-selective photoelectrochemical (PEC) etching. The suspended bridge is actuated by applying a voltage between the bridge and the base plate.

The rapid development of various scanning probe methods like SFM or AFM involving microcantilever based sensor technology has slowly enabled mechanical motion to regain its place in the field of science and engineering by miniaturization of mechanical systems down to sub-micron dimensions. Such scaling down of dimensions of microstructures exhibit very high sensitivity to mechanical deformations due to various induced loads. The most widely used Optical beam deflection method (OBDM) for measuring such deflections in microcantilever based sensors is limited by diffraction effects due to dimensional constraints of the structures involved. The use of polymer materials like poly HDDA having very low elastic modulus has the potential to achieve high mechanical deformation sensitivity for even moderately scaled down structures. Poly-HDDA based microcantilever sensors are being fabricated in an in house realized Microstereolithographic system. The objective is to fabricate a double micro-cantilever structure of length 600 μm, width 60 μm and thickness 40 μm each with a gap of 100 μm between the two along the thickness dimension. The relative deflection profile of one of the fabricated cantilevers due to induced surface stress by the self-assembly of Alkanethiol on Gold is proposed to be measured by an optical diffraction based method. Proposed surface stress resolution achieved in such a typical microcantilever based sensor is of the order of 1 mN/m for a deflection of 0.5 nm at free end of one of the micro-structures subjected to self-assembly mechanism. The high thermal stability and very low elastic modulus of Poly-HDDA enables its application as a low noise, very high sensitive sensor material for detection of mechanical deforming agents in microcantilever based sensor technology.

The development of MEMS comprises the structural design as well as the definition of an appropriate manufacturing process. Technology constraints have a considerable impact on the device design and vice-versa. Product design and technology development are therefore concurrent tasks. Based on a comprehensive methodology the authors introduce a software environment that links commercial design tools from both area into a common design flow. In this paper emphasis is put on automatic low threshold data acquisition. The intention is to collect and categorize development data for further developments with minimum overhead and minimum disturbance of established business processes. As a first step software tools that automatically extract data from spreadsheets or file-systems and put them in context with existing information are presented. The developments are currently carried out in a European research project.

For any kind of optical compound systems the precise geometric alignment of every single element according to the optical design is essential to obtain the desired imaging properties. In this contribution we present a measurement system for the determination of the complete set of geometric alignment parameters in assembled systems. The deviation of each center or curvature with respect to a reference axis is measured with an autocollimator system. These data are further processed in order to provide the shift and tilt of an individual lens or group of lenses with respect to a defined reference axis. Previously it was shown that such an instrument can measure the centering errors of up to 40 surfaces within a system under test with accuracies in the range of an arc second. In addition, the relative distances of the optical surfaces (center thicknesses of lens elements, air gaps in between) are optically determined in the same measurement system by means of low coherent interferometry. Subsequently, the acquired results can be applied for the compensation of the detected geometric alignment errors before the assembly is finally bonded (e.g., glued). The presented applications mainly include measurements of miniaturized lens systems like mobile phone optics. However, any type of objective lens from endoscope imaging systems up to very complex objective lenses used in microlithography can be analyzed with the presented measurement system.

Because of their high viscosity, spin on glue materials used for permanent and temporary bonding applications are usually difficult to dispense and filter at the point of use and achieve high quality, uniform, bubble-free coatings. In this paper, we will focus on the use of the IntelliGen® HV dispense system and its optimisation to improve the temporary bonding material coating uniformity. The system was first utilized without filtration to understand the effect of bubble introduction to the coating. The second phase of the project studied the impact of filtration on the quality of the coating when bubbles were introduced. Coating uniformity data were collected by a Senduro reflectometer and bubble defectivity studies were performed using the NandaTech® SPARK inspection tool.

This study aims to develop a novel CMOS-MEMS logic gate via commercially available CMOS process (TSMC, 2P4M®). Compared to existing CMOS MEMS designs, which uses foundry processes, the proposed design imposes several new challenges including: carrying two voltage levels on a non-warping suspended plate, metal-to- metal contact, and etc. Different combinations of oxide-metal films and post-CMOS process are investigated to achieve a non-warping suspended structure layer. And different wet etchants are investigated to remove sacrificial layers without attacking structure layers and features. In a prototype design, the selected structure layer is metal-3 and oxide film; the device is released using AD-10 and titanium etchant; the device is 250 μm long, 100 μm wide, and 1.5 μm gap. The experimental results show that the suspended plate slightly curls down 0.485 μm. This device can be actuated by 10/0 V with a moving distance 50nm. The resonant frequency is measured at 36 kHz. Due to the damage of the tungsten plugs, the logic function can only be verified by its mechanical movements instead of electrical readouts for now.

This paper focuses on implementing two novel CMOS-MEMS type switches: buckling type and thermal type, by using commercially available TSMC 0.35 μm two-poly four-metal (2P4M) CMOS process. There are two novel designs in these two type switches: first, the soft contact structure with post-processing fabrication; second, using residual stress to achieve large structural deformation in buckling type and thermal type switches. To create the soft contact structure, residual gradient stress effect has been utilized to make bending-down curvatures. According to the experiments, the layer Metal1 has the largest negative residual gradient stress effect that can achieve the largest negative deflection in z-axis. Because the structure will bend down after post-processing release, larger lateral contact area are set up to gain the lower contact miss ability. In the post-processing fabrication, 0.3μm thickness gold will be deposited on the contact tips. Due to the essence of gold, comparing with aluminum, has no oxidation issue, gold also has the advantage of higher conductivity to reduce the electrical power loss. In the buckling type design, the switch uses residual stress to achieve lateral buckling effect to solve long distance problem. In the thermal type design, this paper design a folded-flexure with the electro-thermal excitation to turn the switch on or off. In the prototype, the device size is 500 μm x 400 μm and the gap between two contact pads is 9 μm in off-state. on the experimental results, the switch can work stably at 3 volts, and the displacement of the thermal type switch can achieve 2.7μm, which is sufficient for the mechanism of switching-on or switching-off.

We present the large scale micro-pattering of an electrically conducting multiwalled carbon nanotube (MWCNT) polydimethylsiloxane (PDMS) nanocomposite polymer prepared by high frequency (42 kHz) ultrasonic agitation of MWCNTs in the PDMS polymer matrix. Large scale micropatterning of the MWCNT-PDMS nanocomposite is achieved via soft lithography employing a 12" × 24" poly-methyl methacrylate (PMMA, commercially known as Plexiglass) micromold. The process has a 20µm minimum feature size. The PMMA micromold is fabricated by laser ablating 5-mm thick, 12" × 24" sheets using the Universal Laser System's VersaLASER© laser cutter system which employs a CO₂ laser. We have characterized and compared the resistivity of 1cm × 0.5cm × 0.5cm MWCNT-PDMS structures with varying weight percentage (wt-%) of MWCNT (1-10% wt%) in the PDMS matrix with a result that the percolation threshold is achieved at 2 wt-%. Furthermore, we have demonstrated the ability to fabricate large numbers of microelectrodes with a length of 3.0 cm, width of 500µm, and height of 400µm. The resistivity of these electrodes was found to be equal to 9.93Ωm with a deviation of approximately 10%, indicating uniformity across large areas of the substrate. We have also demonstrated a large scale 12" × 24 hybrid microfabrication process for combining micromolded MWCNT-PDMS nanocomposite microstructures with nonconductive PDMS polymer.